// 判断一个 9x9 的数独是否有效。只需要根据以下规则，验证已经填入的数字是否有效即可。

// 数字 1-9 在每一行只能出现一次。
// 数字 1-9 在每一列只能出现一次。
// 数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。


// 上图是一个部分填充的有效的数独。

// 数独部分空格内已填入了数字，空白格用 '.' 表示。

// 示例 1:

// 输入:
// [
//   ["5","3",".",".","7",".",".",".","."],
//   ["6",".",".","1","9","5",".",".","."],
//   [".","9","8",".",".",".",".","6","."],
//   ["8",".",".",".","6",".",".",".","3"],
//   ["4",".",".","8",".","3",".",".","1"],
//   ["7",".",".",".","2",".",".",".","6"],
//   [".","6",".",".",".",".","2","8","."],
//   [".",".",".","4","1","9",".",".","5"],
//   [".",".",".",".","8",".",".","7","9"]
// ]
// 输出: true
// 示例 2:

// 输入:
// [
//   ["8","3",".",".","7",".",".",".","."],
//   ["6",".",".","1","9","5",".",".","."],
//   [".","9","8",".",".",".",".","6","."],
//   ["8",".",".",".","6",".",".",".","3"],
//   ["4",".",".","8",".","3",".",".","1"],
//   ["7",".",".",".","2",".",".",".","6"],
//   [".","6",".",".",".",".","2","8","."],
//   [".",".",".","4","1","9",".",".","5"],
//   [".",".",".",".","8",".",".","7","9"]
// ]
// 输出: false
// 解释: 除了第一行的第一个数字从 5 改为 8 以外，空格内其他数字均与 示例1 相同。
//      但由于位于左上角的 3x3 宫内有两个 8 存在, 因此这个数独是无效的。
// 说明:

// 一个有效的数独（部分已被填充）不一定是可解的。
// 只需要根据以上规则，验证已经填入的数字是否有效即可。
// 给定数独序列只包含数字 1-9 和字符 '.' 。
// 给定数独永远是 9x9 形式的。

#include <vector>

using namespace std;

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        if (board.empty() || board[0].empty()) return false;
        int m = board.size();
        int n = board[0].size();
        vector<vector<bool>> rowFlag(m, vector<bool>(n, false));
        vector<vector<bool>> colFlag(m, vector<bool>(n, false));
        vector<vector<bool>> cellFlag(m, vector<bool>(n, false));
        for (int i{0}; i < m; ++i) {
            for (int j{0}; j < n; ++j) {
                if (board[i][j] >= '1' && board[i][j] <= '9') {
                    int c = board[i][j] - '1';
                    if (rowFlag[i][c] || colFlag[c][j] || cellFlag[3 * (i/3) + j/3][c])
                        return false;
                    // 当前数字访问过就要做标记
                    rowFlag[i][c] = true;
                    colFlag[c][j] = true;
                    cellFlag[3 * (i/3) + j/3][c] = true;
                }
            }
        }
        return true;
    }
};

#include "../stdc++.h"

class Solution {
public:
    bool isValidSudoku(vector<vector<char>>& board) {
        vector<vector<int>> rows(9, vector<int>(9, 0));
        vector<vector<int>> cols(9, vector<int>(9, 0));
        vector<vector<vector<int>>> subBoxs(3, vector<vector<int>>(3, vector<int>(9, 0)));
        for (int i{0}; i < 9; ++i) {
            for (int j{0}; j < 9; ++j) {
                char c = board[i][j];
                if (c != '.') {
                    int index = c - '0' - 1;
                    ++rows[i][index];
                    ++cols[j][index];
                    ++subBoxs[i/3][j/3][index];
                    if (rows[i][index] > 1 || cols[j][index] > 1 || subBoxs[i/3][j/3][index] > 1) {
                        return false;
                    }
                }
            }
        }
        return true;
    }
};